This disclosure relates to the field of data processing systems. More particularly, this disclosure relates to the determination of correlation between a candidate sequence of symbols and a target sequence of symbols.
It is known to provide correlation circuitry which operates to determine a correlation between a candidate sequence of symbols and a target sequence of symbols. Such correlators typically use N parallel multiply-add structures and an N-sample shift register, where N is the length of the target sequence of symbols. The output of the correlator varies as the candidate sequence of symbols is clocked into the shift register. A thresholding comparator is used to compare the output of the N parallel multiply-add structures with a threshold value to determine the presence or absence of the target sequence of symbols.
An example use of such a correlator is in a “wakeup” receiver. A wakeup receiver is a continuously active hardware block that seeks to detect the presence of a known radio signal from another device. Once this signal is detected, the wakeup receiver triggers a larger system to power up and take some further action. The presence of a known radio signal may be detected by detecting the presence of a target sequence of symbols within a received radio signal. As the wakeup receiver is continuously powered, it is desirable that its power consumption below. At the same time, it is desirable that the wakeup receiver should not generate a large number of false positive detections as the power consumed by inappropriately waking up the full system is high.
It will be appreciated that providing low power correlation has a particular advantage in the context of a wakeup receiver, more generally a low power correlator may be used elsewhere with advantage.